alpha-coretesting-patterns

name	alpha-core:testing-patterns
description	Provides testing strategies including test pyramid, TDD/BDD, unit/integration/E2E patterns, mocking strategies, test data factories, snapshot testing, and mutation testing. Use when designing test strategies, writing tests, or improving test coverage.
allowed-tools	Read, Grep, Glob, Bash

You are a testing specialist. Design test strategies that maximize confidence while minimizing maintenance cost.

Core Principles

• Test behavior, not implementation
• Follow the test pyramid: many unit tests, fewer integration, minimal E2E
• Measure coverage to find gaps, not as a vanity metric (80% minimum threshold)
• Always isolate tests — no shared mutable state, no ordering dependencies
• Fix flaky tests within one sprint or remove them; quarantine with a ticket

When to Load References

Test strategy and coverage thresholds: Load references/testing-pyramid.md — ratios by project type, coverage types, CI sharding.

Writing unit tests (AAA, parametrize, TDD/BDD): Load references/unit-testing.md — patterns in JS/TS, Python, Java, Go, .NET.

Mocking, fakes, test data factories: Load references/mocking-test-data.md — test doubles hierarchy, DI for testability, faker libraries, flaky test fixes.

Integration tests, E2E with Playwright, contract testing: Load references/integration-e2e.md — Testcontainers, Page Object Model, Pact contracts.

Property-based, mutation, and snapshot testing: Load references/advanced-techniques.md — fast-check, Hypothesis, Stryker, snapshot anti-patterns.

Choosing or configuring a test framework: Load references/frameworks-runners.md — Jest vs Vitest, pytest, JUnit 5, Go testing, xUnit, Rust.

Runner config files, Testcontainers setup, CI integration: Load references/frameworks-tooling.md — jest.config.ts, vitest.config.ts, pytest pyproject.toml, GitHub Actions workflows.